computer

A computer accepts information in the form of digital data. Complex computers also include the means for storing data (including software programs). A program may be built into the computer (in the logic circuitry, located on the microprocessors), or may be loaded into the computer's storage and then started by an administrator or user. Today's computers have both kinds of programming.

Prior to the PC, which is small and affordable, computers were large and expensive. Companies enabled multiple users to share the computer resources through attached terminals. Starting in the late 1980's, technological advances made it feasible to build smaller-sized computers that individuals could use independently, whether at work or at home. These were then "networked into" the larger system.

Computers and programs have been devised that allow multiple programs (and computers) to work on the same problem, at the same time, in parallel (see: network computing).
For many users, though, a computer acts only as a "glorified typewriter," used to cut-and-paste objects and to save documents. But computers can also perform a variety of other tasks, such as accounting and desktop publishing.

A computer system includes peripherals, such as hard and floppy disk drives, a monitor, a mouse, the operating system, software, and a printer. All of these components are designed to work together. You need a computer to access the Internet, browse the Web, and send or receive e-mail, among other things.

Historical perspective: Most histories of the modern computer begin with the analytical engine envisioned by Charles Babbage, who followed the mathematical ideas of George Boole (see: Boolean logic), the mathematician who first stated the principles of logic inherent in today's digital computer. In Charles Babbage's day (early 1800s), there was a rather high error rate in mathematical computations. He wanted to design a device that would do the computations successfully, without the human error factor. He never built a real computer; however, he did build a working model of a computing machine that he called a "difference engine." It calculated mathematical tables using differences. Babbage's assistant and collaborator, Ada Lovelace, is said to have introduced the ideas of program loops and subroutines and she is sometimes considered the first programmer. Modern computers inherently follow the ideas of the stored program laid out by John von Neumann in 1945. Essentially, the program is read by the computer one instruction at a time; an operation is performed, then the computer reads the next instruction, and so on.